[abstract] =>
The physical-chemical parameters of wastewater at the entrance and exit of Medias’s wastewater treatment plant during 2009-2011 were determined. Association analysis, factor analysis, multiple linear regression analysis, and t-Test (paired two samples for means) were applied in order to establish a model to explain the pollutants removal degree and the variation in treated water quality. The strongest association occurs between chemical and biochemical oxygen demand. The results indicate that ammonia also has a great influence on the efficiency of wastewater treatment process. The regression analysis leads to a statistically significant model explaining the interdependence of the parameters.